Conversation:

I've never heard of the term "melvin" as anything other than a rather unfashionable first name. Where I'm from (Eastern US), we call the act of pulling a persons underware up from behind further than it was meant to go a "wedgie" for obvious reasons.

I've also never heard of a "melvin" and wedgie is the term used for this pass-time where I'm from (UK).

Same here.